Brush holder assembly with insert



Nov. 25, 1969 c. J. AMREIN 3,430,314

BRUSH HOLDER ASSEMBLY WITH INSERT Filed June 5, 1968 INVENTOR CARL J.AMREIN BY WQ M ATTORNEY United States Patent BRUSH HOLDER ASSEMBLY WITHINSERT Carl J. Amrein, Baltimore, Md., assignor to The Black and DeckerManufacturing Company, Towson, Md.,

a corporation of Maryland Filed June 3, 1968, Ser. No. 733,863 1 I Int.Cl. H02k /14 US. Cl. 310247 6 Claims ABSTRACT OF THE DISCLOSURE Summaryof the invention The present invention deals with an improved brushholder assembly which includes a strengthening, stabilizing and heatdissipating metallic insert retained within a hollow insulating body.The insert slidably guides a brush as well as a terminal whichelectrically connects a lead and the brush and the insertis constructedto facilitate'maximum brush life while protecting the brush assembly andpreventing unintended withdrawal of the terminal and lead therefromafter full brush wear.

Main objects of the present invention, therefore, are to provide animproved brush holder assembly for use in an" electric motor, whichassembly provides strength, stability and protection for the overallassembly and which prevents the electric lead and terminal fromunintentionally withdrawing from the assembly where they can contactexteriorly accessible metal parts.

Further objects of the present invention are to provide an improvedbrush holder assembly of the above character which maximizes brush lifeand facilitates good heat dissipation.

Additional objects are to provide an improved brush holder assembly ofthe above character which is relatively inexpensive to manufacture andassemble, rugged in construction and reliable in use.

Other objects and advantages of the present invention will become moreapparent from a consideration of the detailed description to followtaken in conjunction with the drawings annexed hereto.

Brief description of the drawings FIG. 1 is a view, partly in elevationand partly in section, illustrating a brush holder assembly embodyingthe present invention;

FIG. 2 is an exploded perspective view illustrating the insulating outerbody and metallic insert of the present invention;

FIG. 3 is a sectional view of FIG. 1 taken along the line 33 thereof;

FIG. 4 is a sectional view of FIG. 3 taken along the line 44 thereof;and

FIG. 5 is a sectional view of FIG. 3 taken along the line 5-5 thereof.

Broad statement of the invention Broadly described, the presentinvention relates to a brush holder assembly which comprises a hollowinsulating body, a hollow metallic insert retained within 3,480,814Patented Nov. 25, 1969 ice said body, said body and said insert havingat least one open end, a carbon brush slidably disposed in said insertand adapted to extend outwardly of said one end, spring means behind andadapted to bias said brush outwardly of said one end, said body and saidinsert having aligned slots along one side thereof, an electric leadextending through said slots and having a terminal slidably guidedwithin said insert and held in electrical contact with said brush bysaid spring means, said lead adapted to move along said slots as saidbrush wears, and means on said insert remote from said slot thereinadapted to cooperate with said terminal and prevent withdrawal of saidterminal from said one open end of said insert when said brush wears.

In another aspect, the present invention includes a brush holderassembly comprising a hollow, elongated metallic member having a carbonbrush slidably disposed therein, a compression spring within said memberand adapted to bias said brush outwardly of one end of said member, saidmember having a first elongated slot extending inwardly from said oneend, and second and third elongated slots intermediate the ends of saidmember and on opposite sides of said first slot, electric lead meansextending through said first slot and including a terminal slidablyguided within said member and held in electrical contact with said brushby said spring, said terminal having a pair of projections extendinginto said second and third slots, whereby to prevent withdrawal of saidterminal from said one end of said metallic member.

Detailed description Referring now more specifically to the drawings, abrush holder assembly embodying the present invention is illustratedgenerally at 11 in FIGS. 1 and 3-5 and is seen to include an elongatedgenerally rectangular body 13 adapted to be fixed in suitable fashionupon a motor housing (not shown). The body 13 preferably is constructedfrom a moldable, insulating material, for example, a phenolic, and has agenerally rectangular cavity 15 adapted to receive a generallycomplementary shaped metallic insert 17. The insert 17 also is hollowand may be pressed into the cavity 15 or the insert 17 may be providedwith outwardly bent tabs 19, 21 which permit easy assembly of the insertto the body 13 but substantially prevent its withdrawal. A carbon brush23 is slidably guided in the insert 17 and is normally biased outwardlyof one end thereof by a compression coil spring 25 positioned within theinsert 17 and behind the brush 23. If desired, the insert 17 and thecavity 15 can be arcuately shaped, as shown in FIGS. 2 and 3, toaccommodate the spring 25, and the insert 17 can have inwardly bent tabs27, 29 at its inner end against which the spring 25 seats.

The spring 25 normally holds the brush 23 against a commutator 31forming part of a rotatable armature 33 of an electric motor. Electriccurrent is [delivered to the brush 23 through an electric lead 35 and aterminal 37 connected to the end of the lead 35 and held in electricalcontact with the brush 23 by the spring 25. As shown, the lead 35extends through aligned slots 39, 41 extending to one end of the body 13and insert 17, respectively, and the terminal 37 preferably is betweenthe spring 25 and brush 23. Thus, as the brush 23 wears, the lead 35moves through the slots 39, 41, while the terminal 37 moves along and isguided within the insert 17 for movement toward the commutator 31.

In order to prevent possible injury to the operator, it is importantthat the terminal 37 be prevented from pulling out of the brush assembly11 even after full brush wear. To this end, the terminal 37 is providedwith at least one and preferably a pair of projections 43, 45, one

to either side of the leads 35, which are received in a pair ofelongated slots 47, 49 formed intermediate the ends of the insert 17,one on either side of the slot 41. The body 13 is provided with reliefareas 51, 53 adjacent the slots 47, 49 to accommodate the projections43, 45, respectively. The ends of the slots 47, 49 near the commutator31 form abutments 55, 57 which limit the advancing movement of theterminal 37 toward the commutator and prevent its withdrawal from theinsert 17 even if the brush 23 comes out of the insert 17. By providinga plurality of abutments, the terminal 37 is now more positivelyprevent-ed from unintentionally pulling out of the assembly 11 than itwould be were just one abutment provided.

It will be appreciated that the metallic insert 17 serves to rigidifyand stabilize the body 13 which is constructed from a less rigidmaterial and which has the open slot 39 for the lead 35. Furthermore,the insert 17, being metallic in composition, serves as a heat sink tohelp dissipate heat from the brush 23 during motor operation andtherefore increases brush life.

By the foregoing, there has been disclosed an improved brush holderassembly calculated to fulfill the inventive objects hereinabove setforth, and While a preferred embodiment of the present invention hasbeen illustrated and described in detail, various additions,substitutions, modifications and omissions may be made thereto withoutdeparting from the spirit of the invention as encompassed by theappended claims.

I claim:

1. A brush holder assembly which comprises a hollow insulating body, ahollow metallic insert retained within said body, said body and saidinsert having at least one open end, a carbon brush slidably disposed insaid insert and adapted to extend outwardly of said one end, springmeansbehind and adapted to bias said brush outwardly of said one end,said body and said insert having aligned slots along one side thereof,an electric lead extending through said slots and having a terminalslidably guided within said insert and held in electrical contact withsaid brush by said spring means, said lead adapted to move along saidslots as said brush wears, and means on said insert remote from saidslot therein adapted to cooperate with said terminal and preventwithdrawal of said terminal 4 from said one open end of said insert whensaid brush wears.

2. An assembly as defined in claim 1 wherein said terminal and saidinsert are provided with cooperable abutment means preventing withdrawalof said terminal.

3. An assembly as defined in claim 1 wherein said insert has at leastone elongated slot intermediate its length and which slidably receives aprojection on said terminal.

4. An assembly as defined in claim 1 wherein said'i'nsert has a pair ofelongated slots intermediate its length, one to either side of saidfirst mentioned slot in said insert, said terminal having a pair ofprojections slidably received in said pair of slots.

5. An assembly as defined in claim 1 wherein said terminal is betweensaid brush and said spring.

6. A brush holder assembly comprising a hollow, elongated metallicmember having a carbon brush slidably disposed therein, a compressionspring within said member and adapted to bias said brush outwardly ofone end of said member, said member having a first elongated slotextending inwardly from said one end, and second and third elongatedslots intermediate the ends of said member and on opposite sides of saidfirst slot, electric lead means extending through said first slot andincluding a terminal slidably guided within said member and held inelectrical contact with said brush by said spring, said terminal havinga pair of projections extending into said secondand third slots, wherebyto prevent withdrawal of said terminal from said one end of saidmetallic member.

References Cited UNITED STATES PATENTS 1,457,896 6/1923 Cook 310-2472,477,352 7/1949 Stark 310-247 2,987,639 6/ 1961 Bayless et a1 310-2473,339,098 8/1967 Burrows et a1 310-239 3,387,156 6/1968 Elow et a1.310-249 3,431,446 3/1969 Petersen et a1. 310-247 3,436,576 4/1969 Klebe310-239 MILTON O. HIRSHFIELD, Primary Examiner L. L. SMITH, AssistantExaminer

